-LRB- CNN -RRB- What would happen if the legend of the Lost City of Atlantis was crossed with the screenplay of Kevin Costner 's 1995 hit movie `` Waterworld '' ?

Maybe something like The Ocean Spiral -- an underwater metropolis that generates energy from the seabed and is capable of providing homes and accommodation for 5,000 people .

Sure , such blue-sky thinking may only seem plausible in the world of Hollywood CGI , but this is the futuristic concept proposed by Japanese construction firm Shimizu Corp. .

According to literature released by the company , expertise is being sought from Tokyo University , Japanese government ministries as well as energy firms to bring the project to life .

Shimizu also say projects like the Ocean Spiral may be necessary in the future to confront increasing global problems such as rising sea levels and the need to create new , clean energy sources .

Under the sea

Divided into three distinctive zones , the structure will stretch all the way to the crushing black depths 2.8 miles under the sea off the coast of Japan .

A giant sphere with a diameter 500 meters -LRB- 1,640 feet -RRB- situated just below the surface will form the first section and house residential zones , businesses and hotels .

This inhabited area will be connected to a nine-mile spiral -LRB- section 2 -RRB- that that descends to the seabed where a deep-sea submarine port and factory -LRB- section 3 -RRB- will create the energy required to power the sphere by using micro-organisms that turn carbon dioxide into methane .

If that 's not high-tech enough , power generators situated along the spiral will then use differences in seawater temperature to create additional energy by applying thermal conversion technologies .

Technology wait

Shimizu has a history of imaginative , high-concept projects including a space hotel and floating botanical cities .

The company says the Ocean Spiral would take five years to build and the technology required will be ready in 15 years .

Funding for what is likely to be a cash intensive exercise will also have to be secured .

Until such times arrive , all we 're left with is a series of cool artist renderings to whet -LRB- or should that be wet ? -RRB- our appetites .

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Ocean Spiral is a proposed underwater city from Japanese construction firm Shimizu Corp. .

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The futuristic settlement has been designed to produce all its own energy and will have enough room to house 5,000 people

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Project expertise is being sought from academics , Japanese government departments and energy experts , the company says